The diplomat known as 'Mr. X'

A new biography looks at George Kennan, a 'hopelessly Midwestern' diplomat who shaped decades of US policy.

Sixty years ago, in the early days of the cold war, a long essay appeared in the journal Foreign Affairs which set out the challenges that lay before the United States. Known ever since as the "X article" (the author was identified as "Mr. X"), the piece, the actual title of which was "The Sources of Soviet Conduct," argued that it was necessary for America to construct a foreign policy that would contain the expansive tendencies of the Soviet Union in the years ahead.

The anonymous author outlined an approach that would become known as containment, which, for 40 years, defined American foreign policy.

The author of this seminal article was George Kennan, a State Department employee, whose life and career are chronicled in John Lukacs's thoughtful new biography, George Kennan: A Study of Character. By any measure, Kennan's was a remarkable life, spanning 101 years, from 1904 to 2005. Skilled diplomat, influential policymaker, prolific historian, and astute commentator on international affairs, Kennan was the sort of figure one rarely sees today.

Lukacs gracefully traces the story of Kennan's life from his middle-class beginnings in Milwaukee to his uncomfortable years at Princeton, where, Kennan recalled, he was "hopelessly and crudely Midwestern." After college, Kennan entered the Foreign Service and embarked on a distinguished diplomatic career. Serving in various postings in Europe and the Soviet Union, Kennan toiled ably from the late 1920s through World War II. With the war's end, he was the second-ranking official in the Moscow embassy, a position of considerable import at the start of the postwar era.

Despite his deep knowledge of European matters, Kennan's real expertise lay in Soviet affairs, and Lukacs luminously examines his passion for Russian history and literature, along with his profound understanding of the Russian people. Kennan's determination to understand Russia and its inhabitants made him a brilliant analyst of the Soviet system, and he came to believe that the country Stalin ruled with such extraordinary cruelty could be understood only by placing it in the context of centuries of Russian history – a history of czars and serfs, of Chekhov and Tolstoy.

In 1946, Kennan memorably deployed his understanding of the Soviet Union, composing the longest telegram in the history of American diplomacy. Transmitting the 8,000-word behemoth from Moscow to Washington, Kennan sought to help policymakers grasp the nature of the Soviet threat. The so-called "long telegram," which analyzed the danger the Soviet Union posed to the United States, caused a sensation within the Washington establishment.

"My reputation was made," Kennan would write. "My voice now carried." Indeed it did, for Kennan was shipped back to Washington, where he began shaping foreign policy in the early cold war.

At a time when the character of the postwar world was in flux, Kennan would become an influential policymaker as head of the Policy Planning Staff, a key position for which he was well-suited. As a skilled diplomat and an intellectual, Kennan recognized that effective policy-making demanded historical knowledge, cultural sensitivity, and patience.

But over time his influence waned, and he was eased from his official position, hardly an uncommon development in Washington (then and now). In 1952, Kennan was appointed ambassador to the Soviet Union, though his tenure was brief, the result of a public remark in which he compared life in Moscow to life in wartime Berlin. The Soviets demanded his recall.

Kennan's career was far from over, however. Lukacs describes how Kennan, until well into his 90s, engaged in a life of reflection, writing, and commentary. Numerous books and articles flowed forth: on diplomatic history; on nuclear weapons; on the direction of American foreign policy; and his extraordinary memoirs, which remain among the most illuminating volumes ever written on 20th-century foreign policy.

While there is much to admire in Lukacs's sensitive account, the volume is not without problems. Lukacs and Kennan knew one another, though just how well is not entirely clear. The author notes that Kennan wrote to him approximately 200 times over a 50-year period, and he shares a moving scene near the end of Kennan's life, when he visited the diplomat and his wife in their Princeton home.

Perhaps as a consequence of their relationship, Lukacs lacks a degree of critical detachment when it comes to assessing Kennan's life and career. That Kennan held some peculiar views on democracy is well known. At times, he evinced discomfort with the idea of popular participation in government; indeed, Kennan even questioned the idea of universal suffrage, which Lukacs notes but does not ponder with much care. One wishes that he had, for it is ironic that George Kennan harbored doubts about democracy, the very thing that distinguished the United States from the foe that this esteemed diplomat worked so hard to contain.

•Jonathan Rosenberg, who teaches American history at Hunter College and the City University of New York Graduate Center, is the author of "How Far the Promised Land?: World Affairs and the American Civil Rights Movement from the First World War to Vietnam."